From 4961d0772578e8737afe61370743f3bc22867111 Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Fri, 12 Aug 2022 16:37:27 +0100 Subject: [PATCH] bpf: Clear up confusion in bpf_skb_adjust_room()'s documentation Adding or removing room space _below_ layers 2 or 3, as the description mentions, is ambiguous. This was written with a mental image of the packet with layer 2 at the top, layer 3 under it, and so on. But it has led users to believe that it was on lower layers (before the beginning of the L2 and L3 headers respectively). Let's make it more explicit, and specify between which layers the room space is adjusted. Reported-by: Rumen Telbizov Signed-off-by: Quentin Monnet Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220812153727.224500-3-quentin@isovalent.com --- include/uapi/linux/bpf.h | 6 ++++-- tools/include/uapi/linux/bpf.h | 6 ++++-- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 7d1e279..934a2a8 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2573,10 +2573,12 @@ union bpf_attr { * There are two supported modes at this time: * * * **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer - * (room space is added or removed below the layer 2 header). + * (room space is added or removed between the layer 2 and + * layer 3 headers). * * * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer - * (room space is added or removed below the layer 3 header). + * (room space is added or removed between the layer 3 and + * layer 4 headers). * * The following flags are supported at this time: * diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index e174ad2..1d6085e 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -2573,10 +2573,12 @@ union bpf_attr { * There are two supported modes at this time: * * * **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer - * (room space is added or removed below the layer 2 header). + * (room space is added or removed between the layer 2 and + * layer 3 headers). * * * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer - * (room space is added or removed below the layer 3 header). + * (room space is added or removed between the layer 3 and + * layer 4 headers). * * The following flags are supported at this time: * -- 2.7.4